Sono-optical recorder for antisubmarine attack training



April 1 w. K. LYON ET AL 2,590,878

SONO-OPTICAL. RECORDER FOR ANTISUBMARINE ATTACK TRAINING Filed March 14, 1947 4 Sheets-Sheet l AMPLIFIER RECORDER NTORS WALDO K. 1.96% ROBERT M. SHERWOOD BYW Attorney FIG; 1

April 1, 1952 w. K. LYON 'ET AL 7 2,590,878

SONG-OPTICAL TRECORDER FOR ANTISUBMARINE ATTACK TRAINING Filed March 14, 1947 -4 Sheets-Sheet 2 .J -J U a:

. h B 2 -E3 O a:

l l I r 3 I HYDROPHONES A FIG 2 E v INVENTORS WALDO K. LYON BY ROBERT M. snzawooo Atfornev l l o AMPLIFI April 1952 w. K. LYON ET.AL 2,590,878

SONG-OPTICAL RECORDER ANTISUBMARINE ATTACK TRAINING Filed March 14, 1947 4 Sheets-Sheet 5 INVENTORS' WALDO K.'L

YON RQBERT M SHERWOOD Attorney H W mu 7 W w. K. LYON E'rAL April 1, 1952 SONG-OPTICAL RECORDER FOR ANTISUBMARINE ATTACKRTRAINING 4'Sheets- Shet 4 Filed March 14, 1947 Afto'rney recorder is located within the, submarine.

Patented Apr. 1, 1952 SONO-QP-TIGAL RECORDER. FOR ANTISUB- MARINE ATTACK 'rnammo Waldo K. LY I and Robert Sherwood; I o; Gang: r

4m a h- 9 .7 S 'a 'lie. 135 .42 1 Claim. (01; 351-1 (Granted-under; the act; of; ltigatrcii-li, 1883, as mended il-3 1 25; 3W9. (,3;- 757) This invention relates to. instruments. forv position indicating and more particularly to sonooptical means for locating, relative to a submerged submarine, the explosion point of an underwater flash bomb.

Indicators areknown which determine the position of underwater objects in two dimensions by sound means alone. However, it is extremely desirable in many applications to indicate position in three dimensions. Examples of this are:

(1) To aid in schooling of anti-submarine attack teams by scoring the eifectiveness of practice' attacks;

(2) To provide a basis for experimental evaluaton under controlled conditions of new ordnance, sound equipment, and methods of attack.

The object of this invention is-to provide position indicating equipment which is simple, rugged, compact and which will locate objects in three dimensions.

Another object isto provide an indicator working on optical principles which will be eflicient at the greatest possible ranges in sea water.

The invention also resides in certain novel'features ofcomponent structure and arrangement which facilitate the carrying out of the foregoing objects and which contribute most tothe simplicity of the equipment and to the reliability ofoperation as well as to the ease and expeditious manner of taking measurements.

' in carrying out the present invention, a special constructed projectile," generating sound and light simultaneously is set and launched'to explode at a position simulating the center of a normally used depth charge pattern. The equipment of our invention mounted on, the target submarine will provide coordinates locating the explosion point (E. P.). Knowledge of the pattern simulated by the single projectile makes it Possible to estimate whether the attack' would have been lethal to the submarine. In experimental evaluation it is merely necessary to use the tested apparatus in a series of attacks, while keeping equivalent personnel and submarine tactics. The value of the apparatus will be measured by the percentage of eiiective hits.

' The present equipment is operated from the submarine. Five hydrophones and a photoelectriccell are mounted on the deck structure in one embodiment of the invention. An amplifier- The projectile is an acoustic flash bomb which emits an intense light flash and an explosive soundimpulse at the same instant. This bomb may be Ilsedeither as a stern dropped depth charge or a b ad m r ct l The invention measures the time required for the transmission of sound from the explosion point to the known hydrophone points on the submarine. Since the velocity of sound in water isv known, the recorded times may be read as distances and the E.-P. located by a triangulation method. The'light flash emitted by the explosionof the acoustic flash bomb travels through the water: at a velocity of 740,000,000 feet per second. Thus, it .may be regarded .as reaching the submarine instantaneously, aifecting the photoelectric cell and its associated electrical circuit to make a mark on'the recorder. The

sound impulse generated at the same instant as the light flash likewise. travels outward but at a much slower speed of about .4800. feet per second. Accordingly, a 'very short but appreciable time elapses after the first or. photoelectric cell mark is made on the recorderibefore the first of the hydrophones receives a soundimpulse. Electric circuits connected to this hydrophone cause anotherl mark tobemade on the recorder.

The velocity ofsound in water'is known and accordingly thedifierence in time that the two marks representmay be computed to yield the distance of the lil. P. from the hydrophone. In asimilar manner records are made as the sound impulse reaches the other hydrophones with corresponding determinationoi distances. Each oi these distances flxes a sphere on the surface of which the explosion may have occurred.

Taking the threeshortest of these distances as the most reliable, the-intersection ofthethree spheres centered at 'the hydrophones and-having radii corresponding to-the distances measured by said hydrophone is the location of "the E. P. The conversion ofthese measured distances to location coordinates is do'ne by us'e'oi a generalized model. i

Other objects and advantages of the invention will hecome apharent from the following detailed description taken in connection with the accompanying drawingsin whichz Figure l is'aperspe'ctiy view of a submarine showing the location of the hydrophonesand photocell. l

Figure'Z-isa block diagram of the recording equipment.

Figure 3 is a perspective viewof the plotting board.

Figur 4 i bo-i om v ew o the p ttinsbo digure 5 i viewb a re o eke i the qu m n r Figure 6 is an elevation-cross. section-of the "projecti e.

' th nvention susceptible ar modifications and alternative arrangements, we have shown in the drawings and will herein describe in detail the preferred embodiment. It is to be understood, however, that we do not intend to limit the invention by such disclosure for we aim to cover all modifications and alternative arrangements falling within the spirit and scope of the invention as defined in the appended The relation of an explosion point to the hydrophones and photoelectric cell on a submerged submarine is shown in Figure l. of submarine I0, hydrophones II and I2 are located near the bow and stern respectively on the center line. Hydrophone I3 is on the port deck opposite the conning tower Ib as far from the center line as possible. Hydrophone I4 is symmetrical with I3 but on the starboard side. A fifth hydrophone I5 is located on the center line of conning tower I012 in a vertical plane with I3 and I4. Photoelectric cell I6 is mounted on top of the conning tower. I

Hydrophones I3, I4 and I5 are in a triangular relation in a vertical athwartship cross section. The photocell is mounted as high and clear of obstructions as possible giving maximum visibility. The photocell has its maximum output for a given incident lumination change at about the same wave length as the peak of the light transmission curve of sea water. This affords maximum distance of light reception.

In the use of the present location system, it is important that the vertical displacement of the explosion point from the deck of the submarine be determined aswell as the horizontal displacement, because the ranges to be measured are usually less than three hundred feet. An error in depth may therefore be appreciable even though it is only a few feet, and the horizontal location is also determined in part by the vertical component of the displacement. The hydrophone I5 is therefore mounted on the top of the conning tower to provide a vertical base line for triangulation in a vertical direction.

The hydrophones I3 and I4 are displaced from each other on a lateral axis of the submarine to insure that the explosion point can be accurately located as occurring on the starboard or port side of the vessel as the case may be. Without the lateral base line thus established, ambiguities as to side would be impossible of resolution.

Lines D-I I, D-I3, D-I5 indicate the distances from hydrophones II, I3 and I5 respectively to On deck Illa 4 considerably greater intensity than that created by the submarine itself in order to open the normally closed circuit therethrough.

The photoelectric cell I6 and the hydrophones iI, I2, I3, I4, and I5 are preferably mounted on shock insulating devices to prevent injury thereto by the sound waves created by an explosion immediately adjacent one of the several units. The photoelectric cell It is of conventional type. such as the well-known selenium cell, and is connected with a preamplifier I'I also of conventional design, the output of the preamplifier being impressed on an amplifier Ilia similar to that employed in the hydrophone circuits hereinafter described. 7 7

Each hydrophone II, I2, l3, I4, I5 is connected with an individualized amplifier IIa, I2a, I3a,

the explosion point. Line H indicates the height of the explosion point above the deck of the submarine while line B indicates the horizontal range of the explosion point position. 9 shows the azimuth.

Referring now to'Fig. 2 of the drawings, the hydrophones II, I2, I3, I4, and I5 each contain a movable contact shiftable in response to sound energy and a fixed contact in contact with the movable contact in the absence of sound so as to constitute a normally closed circuit. Hydrophones of the type described in Patent No. 1,402,420 to Heap issued January 3, 1922, may be employed, although it will be apparent to those skilled in the art that many other types of construction may be used.

As is well known, a submarine moving underwater creates considerablenoise, and the sound waves created by an underwater explosion are transmitted at high intensities for considerable distances, so that the hydrophones attached to a submarine in the present invention should be relatively insensitive'to require wave energy of Ita, I5a respectively, each of the amplifiers comprising a trigger circuit producing a pulse of predetermined duration when the contacts of the associated hydrophone are opened by the impingement thereon of sound energy created by an explosion. A trigger circuit suitable for use in the present system is described in Patent No. 2,301,220 to Lowe, issued November 10, 1942, which circuit employs a gas tube extinguished by a capacitive discharge after ionization by the hydrophone connected therewith.

The amplifiers IIa, 12a, I3a, I la, I5a, and IBa are each connected to an individualized stylus on the recorder H! which consists of a metallic disc driven by a constant speed motor adapted to carry a removable disc I9 of electrolytic paper which changes color upon the passage of electric current therethrough. The stylii IIb, I2b, I31), Mb, I5b and I5b are spaced along a radius of the disc in a substantially straight line, so that a pulse from one of the several amplifiers will produce a mark on the electrolytic disc I9 at a radial distance from the center of the disc indicative of the particular amplifier.

A plotting model 2 I is shown in Figures 3 and 4. A maneuvering board 22 covers the base of the model on which the positions of the deck hydrophones are simulated by location holes IIc through I5c respectively. I5c is placed in a block fitted to the base, the height of the block corresponding to the height of hydrophone I5 above the deck. Binding posts 23 are attached to the bottom of the base near the holes. Five flexible members, such as cords or wires, IId through I511 are fastened together at one end to a con- .nector 24. The free ends go through the hydrophone holes and binding posts. Scales 25 are attached to the bottom of the base in such a manner that thedistance each wire is extended may be measured. The movable stand 25 is a stick graduated vertically in feet above the deck, or baseboard plane. Y

A record disc I9 is shown in Figure 5. Lines 29 indicate distances. The outer circle 30 is for the mark from the photoelectric cell It. Circles at through are for hydrophones II through I5 respectively. Mark 35 indicates actuation of the photoelectric cell. Marks 31, 38 and39 indicate actuation of three of the hydrophones and due to the rotation of the disc, their displacement from mark 36 is proportional to the V distances of the hydrophones from the explosion point.

A suitable projectile in the form of an acoustic flash bomb is shown in Figure 6. The main body of the projectile 49 carries a transparent cylinder 4| held by cap 42 which is securedby threaded tube 43 to the main body. A striker 44 is held in inoperative position by aluminum wire 45. 'An

explosive cap 46 is located beneath striker 44; at the other end of the cap is a fuse 47. Black powder 48 is located adjacent to the fuse. Openings 49 in tube 43 lead to flash powder 50.

For operation, the motor which rotates the recording disc is started and the amplifiers, hydrophones and photocell are energized. The projectile 40 is dropped or thrown into the sea, the shock of contact with the water shearing pin 45 which permits striker 64 to detonate cap 46, in

turn lighting fuse 41. A predetermined time later the fuse burns to black powder 48 exploding it, and setting off the sound impulse. Openings 49 in tube 43 permit the black powder to ignite the flash powder 50 which sets on light impulses through transparent walls 4 I.

Assuming the explosion is in the position relative to the submarine shown in Figure 1, the light impulses acting instantaneously will actuate stylus lBb making a mark 36 on the record It. When the sound impulses strike hydrophone Ii, stylus llb will make mark 31 on disc 19. Impulses striking hydrophones l3 and I5 will make marks 38 and 39.

Disc I9 is driven at a constant speed by the motor which is governor controlled. The time of revolution is adjusted to bear a suitable relation to the time required for sound to travel in sea water in order to facilitate calibration. For example, the time of one revolution could be adjusted to equal the time required for sound to travel 300 feet in sea water, that is 300/4800 which equals .0625 second. Accordingly, from the angle which the disc has moved through before a record takes place, the distance from the explosion to the hydrophone making the record may be determined. In the example shown, the mark 31 indicates 192 feet as the distance from the explosion to hydrophone H, mark 38 indicates 205 feet to hydrophone i3, and mark 39 represents 212 feet to hydrophone 15. Distance lines 29 are marked off from 36 as a zero.

may be placed over the record with the zero line on mark 36 to determine the distances.

In the use of the plotting model each wire is clamped so that its length from the common point to the hydrophone opening is the distance given by the record. In the instance shown, wires lid, 13d and "id are set at lengths corresponding to 192, 205 and 212, the other two being loose. After setting, the common junction point is held in hand and moved until all three wires are taut. The junction point then indicates the position of the explosion point and its coordinates may be read by use of the stand 26 and the maneuvering board. In the example shown, the relative bearing 0 is 300, the horizontal range R is 212' and the height H above deck of submarine is 50.

The invention described herein may be manufactured and used by or for the Government of the United States for governmental purposes without the payment to us of any royalties thereon or therefor.

If de-, sired, a transparent scale having similar lines What is claimed is:

In an anti-submarine training device employing an underwater sound and light producing explosive adapted to be ejected by a surface craft, a pair of first sound responsive devices attached to the deck of a submarine on the longitudinal axis thereof at the front and rear thereof to establish a longitudinal base line, a pair of second sound responsive devices attached to the deck of said submarine on the lateral axis at respective sides thereof to establish a lateral base line, a third sound responsive device secured to said submarine in a position vertically displaced from the deck thereof, light responsive means secured to said submarine, individualized amplifier means connected to each of said sound responsive means and said light responsive means, a recorder comprising a disc driven at a predetermined speed, and individualized stylii contacting said disc each responsive to a respective one of said individualized amplifier means to produce an indication on said disc in response to explosion of the sound and light producing explosive in the vicinity of said submarine whereby causing a first indication on said disc responsive to light and a plurality of second indications responsive to sound angularly displaced from said first indication in proportion to the distance of said explosion from respective ones of sound responsive devices thereby to permit location of said explosion in space relative to said submarine.

WALDO K. LYON. ROBERT M. SHERWOOD.

REFERENCES CITED The following references are of record in the iile of this patent:

UNITED STATES PATENTS Number Name Date 684,653 Tuboni Oct. 15, 1901 1,149,976 Furber Aug. 10, 1915 1,151,293 Sawyer Aug. 24, 1915 1,225,796 Fricke May 15, 1917 1,341,795 Fessenden June 1, 1920 1,706,066 Karcher Mar. 19, 1929 1,753,781 Ford Apr. 8, 1930 2,027,528 Hammond Jan. 14. 1936 2,235,177 Stark Mar. 18, 1941 2,261,190 Shropshire Nov. 4, 1941 2,296,901 Brayton Sept. 29, 1942 2,326,680 Norrman Aug. 17, 1943 2,376,730 Steinhofi May 22, 1945 2,397,746 Lewis Apr. 2, 1946 2,405,591 Mason Aug. 13, 1946 2,418,136 Munson Apr. 1, 1947 2,434,644 Fairweather Jan. 20, 1948 FOREIGN PATENTS Number Country Date 16,316 Great Britain 1915 

